Ultimaker Heated Bed Kit Blues...

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So last week I received the HBK I ordered for my Ultimaker (Original, of course) and, to date, it has proven a colossal disappointment to me! Now, I don’t wish to disparage the work of great folks at UM! In my opinion, these are still the best conceived and developed 3D printers around - and the work they’ve done on the heated bed upgrade kit continues the trend. I thought the whole thing was designed brilliantly and fitted the existing “infrastructure” perfectly (even down to providing a laser cut plywood cover for the bearings which, although I imagine not strictly necessary, ties the whole thing together and makes it look like it very much fits the “spirit” of the original machine. Very, very nice indeed! Three point levelling with thumb-screws is also a convenient and welcome addition (instead of the old 4 screws approach).

However, compared to the way my machine worked before – this is a definite step in the wrong direction… :(

I got the heated bed upgrade as soon as I was aware of it for, essentially, 2 reasons… Firstly, I wanted to be able to print ABS. PLA has some nice properties, to be sure, but it doesn’t sand well at all (for smoothing out the layers and making small moulds and tooling) and resulting parts are quite brittle and having an option to do ABS was the primary reason for spending extra money on HBK. I did (long ago) buy some ABS filament but quickly discovered (what everyone knew already, of course) that there’s just no way to use it on the cold bed covered with painter’s tape. The other reason was (the romantic notion) that, even when printing PLA, I would no longer have to be re-taping my bed every 2 or 3 prints – so (perceived) extra convenience of a heated bed was also a factor.

Well, the problem is that over the last year my (pre-modification) machine was rock solid and dependable – feed it some PLA, select my model from the SD card, wait 2-3 minutes for the first couple of layers to start printing and make sure it’s going fine and… Walk away… Come back an hour, two or five later to a finished part waiting.

Post modification machine is anything but… After playing with it for 5 days now (including the entire past weekend) – I have a total of one (1) PLA part that actually printed OK (and zero ABS parts). The closest I got with ABS was one part that got to about 6 or 7 mm height before I stopped it because it had peeled off on one end and was warped terribly. Most of the time, either nothing comes out of the nozzle on the first several passes or once it starts coming out it just gets dragged all over the place. PLA (on the heated bed) is a little better – but still often times nothing comes out or, if I move my bed a bit lower, it doesn’t stick at all. As I said, I only managed 1 print in innumerable tries over the last 5 days (the one that came out though – looked pretty decent – about the same quality as what I was getting before.

I have capton tape on the glass and the whole thing is covered with the provided glue stick in the cross-hatched pattern as recommended. I tried without glue as well (directly onto capton tape) and with glue but directly on the glass (without capton tape) – no love… I haven’t tried the hairspray yet because everything I read suggests that glue stick provides stronger adhesion but I guess I will try that next. I have not tried the “ABS juice” and I don’t really intend to – that definitely does not qualify as clean and convenient… If that really is the only way to get ABS parts printed - I might try it down the road. For now, though, I’d like to AT LEAST get the PLA to print again… I just switched back to PLA (white this time) and (still) getting absolutely no love. Next thing will be to tape the glass with painter’s tape, turn off the heat from the bed and hope that it works at least nearly as well as it did before. If it does, more than likely, I will just go on pretending that I don’t have a heated bed at all (though, pretending that I still have my 245 euros will be more difficult, of course LOL).

After this long (and sad) preamble, I DO have a handful of questions for the helpful and knowledgeable folks at UM forums:

What was the reason for changing the Z axis top limit switch in the kit? I did, of course, replace the existing one with the new one that came in the kit, but AFAICS the two are pretty much identical?

I might have missed something in the installation steps but, again AFAICS, the bed will no longer ever trip the bottom Z switch? It is below the surface of the frame and there’s nothing on the moving part that protrudes to trip it… Did I miss some steps in the installation? Or does Cura/Ultimaker simply rely on “soft limits” for the extent of the Z axis?

Cura (14.09) installed new firmware in response to the creating a new machine (Ultimaker with HBK upgrade) which changed some of the menus and the behaviour on the Ulticontroller and not all for the better! Couple of questions about that:

In Pre-heat PLA and Pre-heat ABS menus there are now sub-options of Pre-heat PLA 1 and Pre-heat PLA bed (and the same for ABS of course). First one (Pre-heat PLA 1) sets the target temperature for BOTH extruder head AND bed while the second one sets it for just the bed. Is there a way of adding an option to preheat just the extruder head? I’m asking because, the way it looks now, I will be most likely going back to painter’s tape (at least in the short term – as I need to actually print a couple of parts and I’m having no love from the heated bed) and would like to be able to just pre-heat the extruder head and leave the bed cold…

After the firmware upgrade Pause Print command does nothing! Well, selecting it changes the menu command name to Resume Print but the actual printing continues as normal. Selecting Resume Print also does nothing (other than turn the command name back to Pause Print). What gives?

I don’t much care about #2 (as I’ve never actually had an occasion where I wanted to pause and resume printing) but another (much bigger!) problem is that “Stop Print” command also (intermittently) malfunctions! Every once in a while – selecting “Stop Print” (of which I’ve been doing quite a LOT lately) will NOT actually stop the head! Ulticontroller display goes back to the main screen – but it still says “Printing” and the head continues travelling in the same direction it was going and ignores the limit switch – and bangs a few times against the ends before giving up. This NEVER, EVER happened before and it is quite unnerving… It doesn’t happen ALL the time – sometimes the printing just stops properly and the bed moves down a few milimeters (which is not how it used to work before if I remember correctly – but is a nice and graceful way of stopping the print). But every once in a while – the head just continues in the direction it was going at the moment I selected Stop Print and bangs against the wall (possibly just mimicking the actions of the operator – as I’ve been banging my head against the wall quite a bit over the last few days :lol:). I may be wrong here (or biased by the shape of the part I was printing) but I’m fairly sure that the above behaviour only ever happened when the Stop Print was triggered while the head was travelling along the Y axis – never when it was travelling along the X axis or the compound path… At least I only ever recall head banging the front or back of the machine (in response to stop) and never the sides. Not sure if that means anything…

Quite often when the printing starts there will be no filament coming out for quite some time (although the extruder stepper is happily churning away). This would on occasion happen with my machine even before the upgrade, but stopping the print and restarting it once or, at most, twice – would usually start things going. After the upgrade, even just printing PLA (therefore, things being equal to before) – I can restart it several times and it would just dry run along the bed leaving nothing behind. Stopping the flow and moving the bed down and manually driving the wheel (or driving the extruder stepper from Ulticontoller), will get the stuff flowing – but starting another print will, more often than not, result in dry runs…

If anyone can help offer insight to any of the above – it would be greatly appreciated!

As I stated above – I really DO think that HBK looks and feels fantastically conceived, designed and engineered (stuff we’ve come to expect from UM) but, on the whole, my experience with it has been very negative so far as, for 245 euros, I’ve taken a machine that printed PLA extremely reliably and ABS not-at-all and turned it into a machine that prints neither (well, maybe PLA – once on every 6 or 7 tries).

Many thanks…

Marko

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For the ultimate in adhesion and warp-free printing I often print with blue painters tape on the heated bed @ 60-70 degrees, It works great. I used to have a custom heated bed but I switched to the kit and so far it has been perfect for me. I'm mostly just printing right on the glass with just a tiny bit of glue stick and I have not yet had any adhesion problems with that.

If you don't want to read it all... For maximum sticking you need the PLA to be hot enough on the bottom layer to flow onto the glass. This means heat. For 20C air, 220C nozzle, this means about 45C minimum. Colder than 45C means it won't stick well at all. From 45C to 70C it's all the same stickiness (no difference). But if you have colder air or colder nozzle you need warmer glass. So I recommend 50C or 60C to be safe. In fact I recommend you do a bunch of experiments and print something that takes under 3 minutes to print and find a way to measure the force of removing that object.

That was too much info. Anyway here is the trick for printing on glass (which is superior in every way to blue tape):

1) Get Elmer's wood glue (it's a pva glue like the glue stick- what country are you in?). Mix it 10 parts water to 1 part glue (this is not exact). Keep it in a glass jar with lid and shake well before each use. Use a cheap paint brush to spread onto the glass. Heat up the glass and don't print until the PVA is dry and so thin it is invisible.

2) Heated bed at 50C

3) Use brim option - extremely important

4) Bottom layer should be squished a bit. Consider moving the glass closer to the nozzle.

If you have very large prints that are still warping you *might* have to print at 75C to keep the part above glass temp on the lower layers. I have never had to do this. Make sure you let it cool to 50C before removing or you will destroy the part as it is still soft like clay at 75C.

Please update what country you are in on your settings.

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For ABS on glass I recommend 110C heated bed temp, 245C print temp. I prefer hairspray for ABS but I have only printed 10 or so ABS prints so don't consider myself an expert. I use unscented hairspray. Spray on tissue then wipe on (so you don't get hairspray all over the inside of your printer).

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What was the reason for changing the Z axis top limit switch in the kit? I did, of course, replace the existing one with the new one that came in the kit, but AFAICS the two are pretty much identical?

The metal arm is longer. That's the only difference. So that it reaches the z-axis end-stop-bump thing.

Or does Cura/Ultimaker simply rely on “soft limits” for the extent of the Z axis?

Yes. In fact the UM2 only has one end stop for each axis and uses soft limits also.

If you don't get answers about the firmware stuff (pause print etc) within 2 days please repost as your post is too long for Daid (the firmware guy) to find your issue. In fact please post each bug in a separate thread (topic) if they might be separate bugs. If you *still* don't get answers within 2 days after that I will bug Daid myself. Or you can PM him. I think the firmware bugs you bring up have been addressed recently but I'm not sure. Perhaps not but hopefully they will be fixed in the next version or in a version that you haven't updated to yet.

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The firmware updates simply came from the community, I had little hand in those. The pause works, but it needs to wait for the buffer to be empty, during infill this can take a while.

The feeder nor the hotend changed, so any extrusion priming problems you might be experiencing, I don't think they came from the heated bed upgrade. Might just be an unlucky timing for a partial nozzle block?

No idea why there is an endstop in the kit...

The bed comes with a significant improvement in bed stability, so you most likely never have to adjust it again, unlike the wooden bed you had before.

Printing with a heated bed can be a bit tricky, I leave it to the above comments for assistance there. (I'm still a blue-tape guy myself)

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In Pre-heat PLA and Pre-heat ABS menus there are now sub-options of Pre-heat PLA 1 and Pre-heat PLA bed (and the same for ABS of course). First one (Pre-heat PLA 1) sets the target temperature for BOTH extruder head AND bed while the second one sets it for just the bed. Is there a way of adding an option to preheat just the extruder head? I’m asking because, the way it looks now, I will be most likely going back to painter’s tape (at least in the short term – as I need to actually print a couple of parts and I’m having no love from the heated bed) and would like to be able to just pre-heat the extruder head and leave the bed cold…

I was involved in the implementation of the preheat menus. Some people have custom heated beds which need quite some time to heat up. Thus the heat bed only option. The '1' options relate to multi-extruder systems where you have also a '2' (and so on) option and an 'all' option.

The case to heat up a nozzle and not the bed was not considered, that's true. The people involved into the extension didn't see a necessity for it. Personally, I still don't see any as I'm not a blue-tape-guy anymore (I was one before I built my own heated bed). But that's of course quite a biased opinion...

For heating up the nozzle only you will have to use the control menu. Of course you are free to extend the firmware even further (as it is open source!) and to issue a pull request for an additional preheat option. You have to know that changing something in the menus is quite a pain due to the fact that in the meantime there are 13 to 14 different languages the entries want to be covered for.

As I understand you have some issues with the adhesion on the glass bed. There is one thing you should never do on glass which you might be used to from blue tape: wipe it with alcohol, e.g. isopropanole. Actually you can wipe it with alcohol, but after that please make sure you clean it off with water and maybe a mild cleaning agent (I use dishwashing agent which includes lactide acid that leads to a very nice adhesion for PLA).

I hope this helps you to understand why the firmware is as it is and to enjoy successful printing directly on glass.

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Simple test - when you are ready to extrude (at the correct nozzle temp) and you turn the extruder cog by hand do you get a noodle? - I always hand prime while the UM is heating up so I have fresh well flowing PLA

PLA will stick to cold glass with PVA glue on it - it is my favourite printing platform, so a warm one will be even more yummy!

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First of all, let me say that I’ve had the Ultimaker for over a year and a half now but it had given me so little trouble in that time – from the ease of putting it all together (owing to a really well thought out kit and excellent documentation) to day-to-day operation (blue tape worked great and, Daid, well Cura is just a fantastic piece of software both in capabilities and ease-of-use) which, I guess, why in all this time I never posted anything on this site. I guess I just merrily went about my business – 3D printing at will. Funny as it sounds, I would say that over the last year and a half my regular, networked laser printer gave me more grief with intermittent problems than Ultimaker did…

I guess this lulled me into thinking that all this will be even better with a heated bed option – everything will be as easy as before except now I will also be able to print ABS. Well, it kind of makes sense that it isn’t QUITE like that (and that I may have been a bit lucky with the performance of my machine to start with) but it seems clear that getting optimum use out of the heated bed (or any use at all LOL) will take some tinkering and experimentation. Which is OK, of course…

But the point I was trying to set up with the above preamble is that I was impressed and humbled by the number (and quality) of replies I received on the first occasion when help was needed. Clearly a passionate and caring community (which makes me very glad to be a part of it) – and I thank you one and all. Lots of good advice and links – that will clearly take a bit of time to digest and test in practice but I’m hoping that the end result will make it worthwhile…

For now, however, I really had to get a couple of parts printed (some drilling jigs I designed for the table top of my CNC machine) so I flipped the glass around (it had Capton tape on one side and the glue stick goo), taped it up with blue painter’s tape and re-leveled the bed. Then proceeded to print my parts on a cold bed with no issues. I know it’s a bit of a copout but, hey, I needed to get them printed so I can continue on with my new table top.

Then this morning I went out and picked up another piece of glass cut to right size – which I’m gonna use strictly with blue tape and cold printing. That way I will have the original bed to mess around with – glue, hairspray, acetone sluice, and so on but will still be able to just swap it out for the other glass with blue tape on quickly when I actually need to print something…

As for the other issues I brought up or asked about…

Daid's explanation on how pause/resume works makes perfect sense and demystifies that. Of course, when you wish to stop printing – you can simply interrupt the process immediately (and dump the buffers) but when you’re just pausing (presumably you have to leave the system in the state where it could be resumed) so you have to let the printer process everything that’s already been queued up. Duh! I imagine it always worked that way – buy I might have only done it once in the past just to check if/how it worked and at that time it may have stopped (I mean paused!) rather quickly – so trying it now (coming off the runaway head occurrences which made me paranoid to begin with) I had just assumed that something was wrong when the only apparent response to Pause command was to turn the menu item into Resume. But, yes, it makes sense now…

With regards to runaway axis issue – it has not happened in my testing yesterday. Over the initial 4-5 days it happened at least 3 or 4 times – so it was not just a single, freak occurrence. Not sure how to replicate it (not that I want to either LOL). I re-flashed the firmware from a different laptop – though I doubt that would’ve made any difference since it was the same version of Cura (14.09) both times. If it happens again, I’ll start a new thread dedicated solely to that issue… But, hopefully not…

@jameshs – I think my issue with under-extruding on the early layers had to do with the nozzle being too close to the bed. On my old bed I had 2 layers of blue tape which gave it a bit spongier feel and made it a bit more forgiving. Here with just a single layer (or, worse, Capton tape instead of blue) and hardness of glass – even a bit too close is enough to clog the opening… Re-leveled again and the results are much better…

@Dim3nsioneer – thanks for the explanation of the thought process that went into the design of the menu structure… I do think it might have made sense to at least have an option to turn off the bed heating (since I can see how, with multiple extruders, giving an option for nozzle, bed or both for each extruder would be cumbersome and sort of confusing). Nevertheless, as you said – it’s not a big deal to navigate over to Control menu and bring the bed temp back to 0. Or simply use the Control menu to dial up the nozzle temp as needed. So, no big deal (certainly not big enough for me to fork my own – especially considering the multiple languages). I must add, however, that “Move Z” option is a most welcome addition (!). Move Axis -> 1 mm -> Z was just too cumbersome considering how often we want to move the bed down a little (compared to moving other axes). So – thanks for that one!

@gr5 – I’m in Canada – Elmer’s glue (as well as any number of other differently branded PVAC based glues) are in ample supply. Will definitely give it a shot soon! For now, as I said – I just tried the glue stick that was included in the package (directly onto glass as well as on Capton tape).

@Daid – with all due respect, I think it remains to be seen whether or not the new Z axis and bed will prove to be a significant improvement in stability. I certainly hope so, but time will tell! One thing about that is that wood (and plywood especially!) is extremely dimensionally stable with respect to temperature fluctuations (but not so much with respect to humidity fluctuation). The aluminum (or any metal) which is what the new bed relies on is quite the opposite – it is fantastically stable with respect to humidity but not so much to temperature. So, it is very much in doubt in my mind whether the new bed proves more stable (considering, of course, in our use large temperature variations are much more the norm than humidity variations). I’ll have to just wait and see! But, for what it’s worth, I found my old bed to be EXTREMELY stable – in fact, I don’t recall ever adjusting it after the initial build over a year and a half of use. So, if the new bed is even close to being as stable as that – I will be more than satisfied! And even if it has to be leveled more often – it’s not quite that big a deal – as the new 3 point adjustment with thumbscrews is way better than the old method. And the new bed and z axis is definitely gives a way smoother motion (when the steppers are off, the bed often just glides down on its own which was never the case with the old one – and moving it up and down manually is incomparably smoother and easier with the new bed). So, overall, a nice hardware upgrade to be sure…

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in fact, I don’t recall ever adjusting it after the initial build over a year and a half of use

Wow. Wow. I had to adjust my wood bed every day. But I can go many months without adjusting metal bed. In fact all adjustments have just been refinements to the original leveling (it gets more and more accurate each time I turn a screw a little bit).

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@gr5 - Well, I'm not sure how to explain my good fortune with the old bed. I suppose I had always thought that everyone's was like that. My basement (where my UM is located) is very humidity stable (whole-house humidifier comes on when the furnace is on and the rest of the time, usually while the a/c is on it stays off - and the basement itself goes through least changes in temperature and humidity) - so that may have been a factor (since, as I mentioned earlier, wood/plywood is dimensionally stable with respect to temperature but sensitive to humidity). The other possible factor is that every last plywood piece of my machine is varnished with 2 coats of polyurethane (and stained blue-jean blue :-P ) - and, yes, that means all of the individual pieces making up the bed have been coated PRIOR to being laminated in the sandwich. I also glued the sandwich together (seeing as I didn't think it would ever need to come apart) rather than relying just on the M3 bolts to keep it all together. The end result was that, it's true, I honestly don't think I EVER re-adjusted the bed since the initial calibration. Though, to be honest, I would imagine my UM doesn't go through quite the "duty cycle" of some of the ones from other users on this forum...

Still, I was very pleased with the "set&forget" nature of the machine to date... In fact, when I saw the aluminum bed frame of the new one and seen how it connects - it was a bit of a cause for concern as I immediately pictured the lower bed expanding and contracting from the heat and messing up the alignment. So, I am very pleased to hear from you and Daid that both of your experiences have been that the new bed is MORE stable than the old one. As I said, if my new one is even close to as stable as the old one - I will be perfectly happy - especially since one has to take into the account that the old bed was never subjected to the kind of heat output and (fairly) rapid temperature variations that this one will be (if, that is, I ever get to that point where I'm using the heated bed LOL).

As per your suggestion, I updated my location (and gender :oops: didn't mean to be ambiguous about that LOL). I am also in Toronto (well, Toronto "area" to be precise) but I've never met Valcrow (or anyone else, for that matter, with a 3D printer). Like on this forum, I guess I just quietly went about my business and didn't get engaged (so far) in the 3D printing "community"... Perhaps I should do more of that...

Cheers (and thanks again),

Marko

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Note that the bed isn't more stable just because of wood vs metal. It's also how the bed is constructed. The old wooden bed has play in the design, causing it to change "neutral" tilt when you press it.

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